Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene...

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Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum- Rodney

Transcript of Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene...

Page 1: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

The System Development Life

Cycle

By :

Careene McCallum-Rodney

Page 2: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Introduction

Analysts take a systematic approach to the analysis and design of information systems. This is embodied in what we refer to as the System Development Life Cycle (SDLC).

Systems are best developed through the use of a specific cycle of analyst and user activities.

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Systems Analysis and Design, Kendall and Kendall,

Seven Phases of the SDLC1. Identifying problems, opportunities,

and objectives.2. Determining information

requirements3. Analyzing system needs4. Designing the recommended

system.5. Developing documenting software.6. Testing and maintaining the

system.7. Implementing and evaluating the

system.

Page 4: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 1: Identifying Problems, Phase 1: Identifying Problems, Opportunities Opportunities and Objectives and Objectives

IDENTIFYING PROBLEMSIDENTIFYING PROBLEMS• This stage is critical to the success of the This stage is critical to the success of the

rest of the project, since no one wants to rest of the project, since no one wants to waste subsequent time addressing the waste subsequent time addressing the wrong problem.wrong problem.

• The analyst will need to look honestly at The analyst will need to look honestly at what is occurring in a business. So that what is occurring in a business. So that problems can be pinpointed. These problems can be pinpointed. These problems will be brought up by others (such problems will be brought up by others (such as organizational members), and they are as organizational members), and they are the reason the analyst was called in.the reason the analyst was called in.

Page 5: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 1: Identifying Problems, Phase 1: Identifying Problems, Opportunities Opportunities and Objectives and Objectives

IDENTIFYING OPPORTUNITIESIDENTIFYING OPPORTUNITIES• Opportunities are situations that the analyst Opportunities are situations that the analyst

believes can be improved upon through the believes can be improved upon through the use of computerized information systems.use of computerized information systems.

• Seizing opportunities may allow the Seizing opportunities may allow the business to gain a competitive edge or set business to gain a competitive edge or set industry standards.industry standards.

Page 6: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 1: Identifying Problems, Phase 1: Identifying Problems, Opportunities Opportunities and Objectives and Objectives

IDENTIFYING OBJECTIVESIDENTIFYING OBJECTIVES• The analyst will have to first identify what The analyst will have to first identify what

the business is trying to do.the business is trying to do.

• Then the analyst will be able to see if some Then the analyst will be able to see if some aspect of information system application aspect of information system application can help the business reach its objectives by can help the business reach its objectives by addressing specific problems or addressing specific problems or opportunities.opportunities.

Page 7: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 1: Identifying Problems, Phase 1: Identifying Problems, Opportunities Opportunities and Objectives and Objectives

CONCLUSIONCONCLUSION• The people involved in this phase are the The people involved in this phase are the

users, analysts, and systems managers users, analysts, and systems managers coordinating the project.coordinating the project.

• Activities involved in this phase involvesActivities involved in this phase involves– Interviewing user managementInterviewing user management– Summarizing the knowledge obtainedSummarizing the knowledge obtained– Estimating the scope of the projectEstimating the scope of the project– Documenting the resultsDocumenting the results

• The output of this phase is a feasibility The output of this phase is a feasibility report containing a problem definition and report containing a problem definition and summarizing the objectives. summarizing the objectives.

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Systems Analysis and Design, Kendall and Kendall,

Phase 2: Determining Information Requirements

This phase focuses on determining the information requirement for the particular user involved.

Some of the tools used to define information requirements in a business are:

Sampling and investigating hard data.

Interviewing

Questionnaires

Observing decision makers’ behaviour and office environment

Prototyping (this will include some but not all features, one that, if successful, will eventually be part of the larger, final system that is delivered)

Analysts are trying to understand what information the users need to perform their jobs.

Page 9: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 2: Determining Information Requirements

This kind of study may have a different purpose and is typically carried out by a specialist called an information analyst.

People involved in this phase are:Analysts

Users (operational managers and operations workers)

The systems analyst needs to know the details of current function

The who (the people who are involved)

The what (The business activities)

Where (the environment in which the work takes place)

When (the timing), and

How (how the current procedures are performed)

Page 10: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 2: Determining Information Requirements

The analyst must ask why the business uses the current system. There may be good reasons for using the current method, and these should be considered when designing any system.

On completion of this phase, the analyst must understand:

How the business functions

Have complete information on the people, goals, data, and procedures involved.

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Systems Analysis and Design, Kendall and Kendall,

Phase 3: Analyzing System NeedsPhase 3: Analyzing System Needs

USE OF SPECIAL TOOLS AND TECHNIQUESUSE OF SPECIAL TOOLS AND TECHNIQUES• Special tools and techniques help the analyst Special tools and techniques help the analyst

make requirements determinations.make requirements determinations.

• One such tool is a One such tool is a Data Flow DiagramData Flow Diagram, to chart , to chart inputs, processes, and output of the business’ inputs, processes, and output of the business’ functions in a structured graphical form.functions in a structured graphical form.

• From the Data Flow Diagram, a From the Data Flow Diagram, a Data Data DictionaryDictionary is developed that lists all of the data is developed that lists all of the data items used in the system, as well as their items used in the system, as well as their specifications – whether they are alphanumeric specifications – whether they are alphanumeric or text, how much space they take up when or text, how much space they take up when printed. printed.

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Systems Analysis and Design, Kendall and Kendall,

Phase 3: Analyzing System NeedsPhase 3: Analyzing System Needs

ANALYZING STRUCTURED DECISIONSANALYZING STRUCTURED DECISIONS• Structured decisions are those for which Structured decisions are those for which

the conditions, conditions alternatives, the conditions, conditions alternatives, actions, and action rules can be actions, and action rules can be determined.determined.

• There are 3 major methods for analysis of There are 3 major methods for analysis of structured decisions: structured decisions:

1.1. structured Englishstructured English2.2. Decision tablesDecision tables3.3. Decision treesDecision trees

Not all decisions in an organization are Not all decisions in an organization are structured, but it is still important for the structured, but it is still important for the systems analyst to understand them.systems analyst to understand them.

Page 13: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 3: Analyzing System NeedsPhase 3: Analyzing System Needs

SEMISTRUCTURED DECISIONSSEMISTRUCTURED DECISIONS• These are decisions made under risk, and These are decisions made under risk, and

are often supported by decision support are often supported by decision support systems.systems.

• When analyzing semi structured decisions, When analyzing semi structured decisions, the analyst examines the decisions based the analyst examines the decisions based on:on:

– The degree of decision making skills requiredThe degree of decision making skills required– The degree of problem complexityThe degree of problem complexity– The number of criteria considered when the The number of criteria considered when the

decision is made.decision is made.

Page 14: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 3: Analyzing System NeedsPhase 3: Analyzing System Needs

MULTIPLE CRITERIA DECISIONSMULTIPLE CRITERIA DECISIONS• This is where many factors must be This is where many factors must be

balanced.balanced.

• Many techniques are available for Many techniques are available for analyzing multiple-criteria decisions, such analyzing multiple-criteria decisions, such asas

– Tradeoff processTradeoff process– Weighting methodsWeighting methods

Page 15: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 3: Analyzing System NeedsPhase 3: Analyzing System Needs

CONCLUSIONCONCLUSION• At this point of the SDLC, the systems At this point of the SDLC, the systems

analyst prepares a system proposal that analyst prepares a system proposal that summarizessummarizes

– what has been found what has been found – provides cost/benefit analyses of alternativesprovides cost/benefit analyses of alternatives– Makes recommendations on what should be Makes recommendations on what should be

donedone

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Systems Analysis and Design, Kendall and Kendall,

Phase 4: Designing the Recommended System

At this phase, the systems analyst uses the information collected earlier to accomplish the logical design of the information system.

The analyst designs accurate data-entry procedures so that data going into the information system are correct.

The analyst provides for effective input to the information system by using techniques of good form and screen design.

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Systems Analysis and Design, Kendall and Kendall,

Phase 4: Designing the Recommended System

DESIGN USER INTERFACE

Part of the logical design of the information system is devising the user interface.

The interface connects the user with the system and is thus extremely important.

Examples of user interface are:Keyboard (to type in questions and answers)

On-screen menus (to elicit commands)

A variety of graphical user interfaces (GUIs), that use a mouse or touch screens.

Page 18: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 4: Designing the Recommended System

DESIGN FILES AND DATABASES

This design phase also includes designing files or databases that will store much of the data needed by decision makers in the organization.

A well-organized database is the basis for all information systems.

The analyst also work with users to design output (either on-screen or printed) that meets the information needs.

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Systems Analysis and Design, Kendall and Kendall,

Phase 4: Designing the Recommended System

DESIGN CONTROLS AND BACKUP PROCEDURES

The analyst must design control and backup procedures to protect the system and the data and to produce program specification packets for programmers.

Each packet should contain input and output layouts

File specification

Processing details

Decision trees

System flowchart

Names and functions of any prewritten code routines

Page 20: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 5: Developing and Documenting Phase 5: Developing and Documenting SoftwareSoftware

• In this phase the analyst works with In this phase the analyst works with programmers to develop the original software programmers to develop the original software that is needed.that is needed.

• Some of the structured techniques for designing Some of the structured techniques for designing and documenting software include:and documenting software include:

• Structured chartsStructured charts• PsuedocodesPsuedocodes

• The systems analyst uses one or more of these The systems analyst uses one or more of these devices to communicate to the programmer devices to communicate to the programmer what needs to be programmed.what needs to be programmed.

Page 21: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 5: Developing and Phase 5: Developing and Documenting SoftwareDocumenting Software

• The analyst also works with the user to develop The analyst also works with the user to develop effective documentation for software, including effective documentation for software, including manual, online help, Web Site featuring manual, online help, Web Site featuring Frequently Asked Question (FAQ), on “Read Me” Frequently Asked Question (FAQ), on “Read Me” files shipped with new software.files shipped with new software.

• Documentation tells users how to use the Documentation tells users how to use the software and also what to do if software software and also what to do if software problems occur.problems occur.

• Programmers have a key role in this phase Programmers have a key role in this phase because they design, code, and remove because they design, code, and remove syntactical errors from computer programssyntactical errors from computer programs

Page 22: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 5: Developing and Documenting Phase 5: Developing and Documenting SoftwareSoftware

• To ensure quality, a programmer may conduct To ensure quality, a programmer may conduct either a design or a code walkthrough, either a design or a code walkthrough, explaining complex portions of the program to a explaining complex portions of the program to a team of other programmers (technical team of other programmers (technical documentation)documentation)

Page 23: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 6: Testing and Maintaining the System

Before the information can be used, it must be tested.

It is way less costly to locate problems before the system is signed over to users.

Some of the testing is completed by programmers alone, some by systems analyst in conjunction with programmers.

Sample data and eventually actual data from the current system is used in testing the program.

Maintenance of the system and its documentation begins in this phase and is carried out routinely throughout the life of the information system.

Page 24: Systems Analysis and Design, Kendall and Kendall, The System Development Life Cycle By : Careene McCallum-Rodney.

Systems Analysis and Design, Kendall and Kendall,

Phase 7: Implementing and Phase 7: Implementing and evaluating the systemevaluating the system

• In this phase the analyst helps implement the In this phase the analyst helps implement the information system.information system.

• This involves training users to use the system.This involves training users to use the system.• Some training is done by the vendor, but oversight Some training is done by the vendor, but oversight

of training is the responsibility of the systems of training is the responsibility of the systems analyst.analyst.

• The analyst needs to plan for a smooth conversion The analyst needs to plan for a smooth conversion from the old system to the new system. This from the old system to the new system. This process involves:process involves:

• Converting files from the old formats to new ones or building Converting files from the old formats to new ones or building a database.a database.

• Installing equipmentInstalling equipment• Bringing new system into productionBringing new system into production

• A key criteria that must be satisfied is whether the A key criteria that must be satisfied is whether the user is actually using the system (evaluation).user is actually using the system (evaluation).

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Systems Analysis and Design, Kendall and Kendall,

CONCLUSION OF SDLC

It is important to note that the system work is cyclical.

When an analyst finishes one phase of system development and proceeds to the next, the discovery of a problem may force the analyst to return to the previous phase and modify the work done there.

The analyst may need to meet with the user and reinvestigate how a specific business activity functions.